const combine = Cesium.combine;
const Credit  = Cesium.Credit;
const defaultValue = Cesium.defaultValue;
const defined = Cesium.defined;
const DeveloperError = Cesium.DeveloperError;
const Event = Cesium.Event;
const isArray = Cesium.isArray;
const Rectangle = Cesium.Rectangle;
const Resource = Cesium.Resource;
const WebMercatorTilingScheme = Cesium.WebMercatorTilingScheme;
const when = Cesium.when;
const ImageryProvider = Cesium.ImageryProvider;
const TimeDynamicImagery = Cesium.TimeDynamicImagery;

var defaultParameters = Object.freeze({
    service : 'WMTS',
    version : '1.0.0',
    request : 'GetTile'
});

/**
 * Provides tiled imagery served by {@link http://www.opengeospatial.org/standards/wmts|WMTS 1.0.0} compliant servers.
 * This provider supports HTTP KVP-encoded and RESTful GetTile requests, but does not yet support the SOAP encoding.
 *
 * @alias WebMapTileServiceImageryProvider
 * @constructor
 *
 * @param {Object} options Object with the following properties:
 * @param {Resource|String} options.url The base URL for the WMTS GetTile operation (for KVP-encoded requests) or the tile-URL template (for RESTful requests). The tile-URL template should contain the following variables: &#123;style&#125;, &#123;TileMatrixSet&#125;, &#123;TileMatrix&#125;, &#123;TileRow&#125;, &#123;TileCol&#125;. The first two are optional if actual values are hardcoded or not required by the server. The &#123;s&#125; keyword may be used to specify subdomains.
 * @param {String} [options.format='image/jpeg'] The MIME type for images to retrieve from the server.
 * @param {String} options.layer The layer name for WMTS requests.
 * @param {String} options.style The style name for WMTS requests.
 * @param {String} options.tileMatrixSetID The identifier of the TileMatrixSet to use for WMTS requests.
 * @param {Array} [options.tileMatrixLabels] A list of identifiers in the TileMatrix to use for WMTS requests, one per TileMatrix level.
 * @param {Clock} [options.clock] A Clock instance that is used when determining the value for the time dimension. Required when options.times is specified.
 * @param {TimeIntervalCollection} [options.times] TimeIntervalCollection with its <code>data</code> property being an object containing time dynamic dimension and their values.
 * @param {Object} [options.dimensions] A object containing static dimensions and their values.
 * @param {Number} [options.tileWidth=256] The tile width in pixels.
 * @param {Number} [options.tileHeight=256] The tile height in pixels.
 * @param {TilingScheme} [options.tilingScheme] The tiling scheme corresponding to the organization of the tiles in the TileMatrixSet.
 * @param {Rectangle} [options.rectangle=Rectangle.MAX_VALUE] The rectangle covered by the layer.
 * @param {Number} [options.minimumLevel=0] The minimum level-of-detail supported by the imagery provider.
 * @param {Number} [options.maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
 * @param {Ellipsoid} [options.ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
 * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
 * @param {String|String[]} [options.subdomains='abc'] The subdomains to use for the <code>{s}</code> placeholder in the URL template.
 *                          If this parameter is a single string, each character in the string is a subdomain.  If it is
 *                          an array, each element in the array is a subdomain.
 *
 * @demo {@link https://sandcastle.cesium.com/index.html?src=Web%20Map%20Tile%20Service%20with%20Time.html|Cesium Sandcastle Web Map Tile Service with Time Demo}
 *
 * @example
 * // Example 1. USGS shaded relief tiles (KVP)
 * var shadedRelief1 = new Cesium.WebMapTileServiceImageryProvider({
     *     url : 'http://basemap.nationalmap.gov/arcgis/rest/services/USGSShadedReliefOnly/MapServer/WMTS',
     *     layer : 'USGSShadedReliefOnly',
     *     style : 'default',
     *     format : 'image/jpeg',
     *     tileMatrixSetID : 'default028mm',
     *     // tileMatrixLabels : ['default028mm:0', 'default028mm:1', 'default028mm:2' ...],
     *     maximumLevel: 19,
     *     credit : new Cesium.Credit('U. S. Geological Survey')
     * });
 * viewer.imageryLayers.addImageryProvider(shadedRelief1);
 *
 * @example
 * // Example 2. USGS shaded relief tiles (RESTful)
 * var shadedRelief2 = new Cesium.WebMapTileServiceImageryProvider({
     *     url : 'http://basemap.nationalmap.gov/arcgis/rest/services/USGSShadedReliefOnly/MapServer/WMTS/tile/1.0.0/USGSShadedReliefOnly/{Style}/{TileMatrixSet}/{TileMatrix}/{TileRow}/{TileCol}.jpg',
     *     layer : 'USGSShadedReliefOnly',
     *     style : 'default',
     *     format : 'image/jpeg',
     *     tileMatrixSetID : 'default028mm',
     *     maximumLevel: 19,
     *     credit : new Cesium.Credit('U. S. Geological Survey')
     * });
 * viewer.imageryLayers.addImageryProvider(shadedRelief2);
 *
 * @example
 * // Example 3. NASA time dynamic weather data (RESTful)
 * var times = Cesium.TimeIntervalCollection.fromIso8601({
     *     iso8601: '2015-07-30/2017-06-16/P1D',
     *     dataCallback: function dataCallback(interval, index) {
     *         return {
     *             Time: Cesium.JulianDate.toIso8601(interval.start)
     *         };
     *     }
     * });
 * var weather = new Cesium.WebMapTileServiceImageryProvider({
     *     url : 'https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/AMSR2_Snow_Water_Equivalent/default/{Time}/{TileMatrixSet}/{TileMatrix}/{TileRow}/{TileCol}.png',
     *     layer : 'AMSR2_Snow_Water_Equivalent',
     *     style : 'default',
     *     tileMatrixSetID : '2km',
     *     maximumLevel : 5,
     *     format : 'image/png',
     *     clock: clock,
     *     times: times,
     *     credit : new Cesium.Credit('NASA Global Imagery Browse Services for EOSDIS')
     * });
 * viewer.imageryLayers.addImageryProvider(weather);
 *
 * @see ArcGisMapServerImageryProvider
 * @see BingMapsImageryProvider
 * @see GoogleEarthEnterpriseMapsProvider
 * @see OpenStreetMapImageryProvider
 * @see SingleTileImageryProvider
 * @see TileMapServiceImageryProvider
 * @see WebMapServiceImageryProvider
 * @see UrlTemplateImageryProvider
 */
function WebMapTileServiceImageryProvider(viewer,options) {
    this.viewer = viewer;
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
        throw new DeveloperError('options.url is required.');
    }
    if (!defined(options.layer)) {
        throw new DeveloperError('options.layer is required.');
    }
    if (!defined(options.style)) {
        throw new DeveloperError('options.style is required.');
    }
    if (!defined(options.tileMatrixSetID)) {
        throw new DeveloperError('options.tileMatrixSetID is required.');
    }
    if (defined(options.times) && !defined(options.clock)) {
        throw new DeveloperError('options.times was specified, so options.clock is required.');
    }
    //>>includeEnd('debug');

    var resource = Resource.createIfNeeded(options.url);

    var style = options.style;
    var tileMatrixSetID = options.tileMatrixSetID;
    var url = resource.url;
    if (url.indexOf('{') >= 0) {
        var templateValues = {
            style : style,
            Style : style,
            TileMatrixSet : tileMatrixSetID
        };

        resource.setTemplateValues(templateValues);
        this._useKvp = false;
    } else {
        resource.setQueryParameters(defaultParameters);
        this._useKvp = true;
    }

    this._resource = resource;
    this._layer = options.layer;
    this._style = style;
    this._tileMatrixSetID = tileMatrixSetID;
    this._tileMatrixLabels = options.tileMatrixLabels;
    this._format = defaultValue(options.format, 'image/jpeg');
    this._tileDiscardPolicy = options.tileDiscardPolicy;

    this._tilingScheme = defined(options.tilingScheme) ? options.tilingScheme : new WebMercatorTilingScheme({ellipsoid : options.ellipsoid});
    this._tileWidth = defaultValue(options.tileWidth, 256);
    this._tileHeight = defaultValue(options.tileHeight, 256);

    this._minimumLevel = defaultValue(options.minimumLevel, 0);
    this._maximumLevel = options.maximumLevel;

    this._rectangle = defaultValue(options.rectangle, this._tilingScheme.rectangle);
    this._dimensions = options.dimensions;

    var that = this;
    this._reload = undefined;
    if (defined(options.times)) {
        this._timeDynamicImagery = new TimeDynamicImagery({
            clock : options.clock,
            times : options.times,
            requestImageFunction : function(x, y, level, request, interval) {
                return requestImage(that, x, y, level, request, interval);
            },
            reloadFunction : function() {
                if (defined(that._reload)) {
                    that._reload();
                }
            }
        });
    }

    this._readyPromise = when.resolve(true);

    // Check the number of tiles at the minimum level.  If it's more than four,
    // throw an exception, because starting at the higher minimum
    // level will cause too many tiles to be downloaded and rendered.
    var swTile = this._tilingScheme.positionToTileXY(Rectangle.southwest(this._rectangle), this._minimumLevel);
    var neTile = this._tilingScheme.positionToTileXY(Rectangle.northeast(this._rectangle), this._minimumLevel);
    var tileCount = (Math.abs(neTile.x - swTile.x) + 1) * (Math.abs(neTile.y - swTile.y) + 1);
    //>>includeStart('debug', pragmas.debug);
    if (tileCount > 4) {
        throw new DeveloperError('The imagery provider\'s rectangle and minimumLevel indicate that there are ' + tileCount + ' tiles at the minimum level. Imagery providers with more than four tiles at the minimum level are not supported.');
    }
    //>>includeEnd('debug');

    this._errorEvent = new Event();

    var credit = options.credit;
    this._credit = typeof credit === 'string' ? new Credit(credit) : credit;

    this._subdomains = options.subdomains;
    if (Array.isArray(this._subdomains)) {
        this._subdomains = this._subdomains.slice();
    } else if (defined(this._subdomains) && this._subdomains.length > 0) {
        this._subdomains = this._subdomains.split('');
    } else {
        this._subdomains = ['a', 'b', 'c'];
    }

    this.useStyleLevel = true;
    if(options.hasOwnProperty('useStyleLevel')){
        this.useStyleLevel = options.useStyleLevel;
    }
}

function requestImage(imageryProvider, col, row, level, request, interval) {
    var labels = imageryProvider._tileMatrixLabels;
    var tileMatrix = defined(labels) ? labels[level] : level.toString();
    var subdomains = imageryProvider._subdomains;
    var staticDimensions = imageryProvider._dimensions;
    var dynamicIntervalData = defined(interval) ? interval.data : undefined;

    let styleLevel = tileMatrix;
    if(imageryProvider.useStyleLevel){
        styleLevel = imageryProvider.viewer.camera.getLevel();
        // let labels = imageryProvider._tileMatrixLabels;
        // styleLevel = defined(labels) ? labels[styleLevel] : styleLevel.toString();
    }


    var resource;
    if (!imageryProvider._useKvp) {
        var templateValues = {
            TileMatrix: tileMatrix,
            TileRow: row.toString(),
            TileCol: col.toString(),
            s: subdomains[(col + row + level) % subdomains.length],
            styleLevel:styleLevel
        };

        resource = imageryProvider._resource.getDerivedResource({
            request: request
        });
        resource.setTemplateValues(templateValues);

        if (defined(staticDimensions)) {
            resource.setTemplateValues(staticDimensions);
        }

        if (defined(dynamicIntervalData)) {
            resource.setTemplateValues(dynamicIntervalData);
        }
    } else {
        // build KVP request
        var query = {};
        query.tilematrix = tileMatrix;
        query.layer = imageryProvider._layer;
        query.style = imageryProvider._style;
        query.tilerow = row;
        query.tilecol = col;
        query.tilematrixset = imageryProvider._tileMatrixSetID;
        query.format = imageryProvider._format;
        query.styleLevel = styleLevel;

        if (defined(staticDimensions)) {
            query = combine(query, staticDimensions);
        }

        if (defined(dynamicIntervalData)) {
            query = combine(query, dynamicIntervalData);
        }
        resource = imageryProvider._resource.getDerivedResource({
            queryParameters: query,
            request: request
        });
    }

    var templateValuesTemp = resource.templateValues;
    console.log(templateValuesTemp.TileCol+'_'+templateValuesTemp.TileRow+'_'+ 'level:'+ templateValuesTemp.TileMatrix + 'styleLevel:' + styleLevel);
    return ImageryProvider.loadImage(imageryProvider, resource);
}

Object.defineProperties(WebMapTileServiceImageryProvider.prototype, {
    /**
     * Gets the URL of the service hosting the imagery.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url : {
        get : function() {
            return this._resource.url;
        }
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy : {
        get : function() {
            return this._resource.proxy;
        }
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth : {
        get : function() {
            return this._tileWidth;
        }
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight : {
        get : function() {
            return this._tileHeight;
        }
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    maximumLevel : {
        get : function() {
            return this._maximumLevel;
        }
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel : {
        get : function() {
            return this._minimumLevel;
        }
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme : {
        get : function() {
            return this._tilingScheme;
        }
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle : {
        get : function() {
            return this._rectangle;
        }
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy : {
        get : function() {
            return this._tileDiscardPolicy;
        }
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent : {
        get : function() {
            return this._errorEvent;
        }
    },

    /**
     * Gets the mime type of images returned by this imagery provider.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    format : {
        get : function() {
            return this._format;
        }
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready : {
        value : true
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise : {
        get : function() {
            return this._readyPromise;
        }
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit : {
        get : function() {
            return this._credit;
        }
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel : {
        get : function() {
            return true;
        }
    },
    /**
     * Gets or sets a clock that is used to get keep the time used for time dynamic parameters.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Clock}
     */
    clock : {
        get : function() {
            return this._timeDynamicImagery.clock;
        },
        set : function(value) {
            this._timeDynamicImagery.clock = value;
        }
    },
    /**
     * Gets or sets a time interval collection that is used to get time dynamic parameters. The data of each
     * TimeInterval is an object containing the keys and values of the properties that are used during
     * tile requests.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TimeIntervalCollection}
     */
    times : {
        get : function() {
            return this._timeDynamicImagery.times;
        },
        set : function(value) {
            this._timeDynamicImagery.times = value;
        }
    },
    /**
     * Gets or sets an object that contains static dimensions and their values.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Object}
     */
    dimensions : {
        get : function() {
            return this._dimensions;
        },
        set : function(value) {
            if (this._dimensions !== value) {
                this._dimensions = value;
                if (defined(this._reload)) {
                    this._reload();
                }
            }
        }
    }
});

/**
 * Gets the credits to be displayed when a given tile is displayed.
 *
 * @param {Number} x The tile X coordinate.
 * @param {Number} y The tile Y coordinate.
 * @param {Number} level The tile level;
 * @returns {Credit[]} The credits to be displayed when the tile is displayed.
 *
 * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
 */
WebMapTileServiceImageryProvider.prototype.getTileCredits = function(x, y, level) {
    return undefined;
};

/**
 * Requests the image for a given tile.  This function should
 * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
 *
 * @param {Number} x The tile X coordinate.
 * @param {Number} y The tile Y coordinate.
 * @param {Number} level The tile level.
 * @param {Request} [request] The request object. Intended for internal use only.
 * @returns {Promise.<Image|Canvas>|undefined} A promise for the image that will resolve when the image is available, or
 *          undefined if there are too many active requests to the server, and the request
 *          should be retried later.  The resolved image may be either an
 *          Image or a Canvas DOM object.
 *
 * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
 */
WebMapTileServiceImageryProvider.prototype.requestImage = function(x, y, level, request) {
    var result;
    var timeDynamicImagery = this._timeDynamicImagery;
    var currentInterval;

    // Try and load from cache
    if (defined(timeDynamicImagery)) {
        currentInterval = timeDynamicImagery.currentInterval;
        result = timeDynamicImagery.getFromCache(x, y, level, request);
    }

    // Couldn't load from cache
    if (!defined(result)) {
        result = requestImage(this, x, y, level, request, currentInterval);
    }

    // If we are approaching an interval, preload this tile in the next interval
    if (defined(result) && defined(timeDynamicImagery)) {
        timeDynamicImagery.checkApproachingInterval(x, y, level, request);
    }

    return result;
};

/**
 * Picking features is not currently supported by this imagery provider, so this function simply returns
 * undefined.
 *
 * @param {Number} x The tile X coordinate.
 * @param {Number} y The tile Y coordinate.
 * @param {Number} level The tile level.
 * @param {Number} longitude The longitude at which to pick features.
 * @param {Number} latitude  The latitude at which to pick features.
 * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
 *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
 *                   instances.  The array may be empty if no features are found at the given location.
 *                   It may also be undefined if picking is not supported.
 */
WebMapTileServiceImageryProvider.prototype.pickFeatures = function(x, y, level, longitude, latitude) {
    return undefined;
};
module.exports =WebMapTileServiceImageryProvider;
